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Abstract

Midwest oak savanna communities are noted for their unusual plant assemblages, but these communities have been reduced by more than 98% because of changing land uses and conversion to closed-canopy forests. We initiated an ongoing 15-year experiment in 1988 to restore a 40-ha black oak (Quercus velutina) savanna by applying burn treatments that historically maintained this vegetation type. Groundlayer composition changed significantly for both the burn treatment and the control, with the burn treatment exhibiting slight increases in herbs such as wild lupine (Lupinus perennis) and hairy puccoon (Lithospermum caroliniense), both of which are species requiring greater insolation. Burn treatments differentially affected different plant community characteristics during the 15-year period, with some characteristics such as sapling density decreasing and other characteristics like species richness remaining comparatively unchanged. Oak overstory density was not affected by burn treatments, and reductions in oak density of 33-50% are needed for consistency with presettlement savanna structure to enhance the diversity of sunny and shady microsites characteristic of oak savannas. Results support the continuation of experimental restoration treatments in this savanna, and indicate further research is needed to clarify long-term patterns of temporal change in oak savanna vegetation.